Light distance

I have 2 Mars hydro 192x5 reflectors. They say one is great for a 4x4 tent with the light 24"-30" above canopy. I have a 5x5 tent so I thought, why not get 2 and make it more than enough light. So if hanging one in a 4x4 tent at 24"-30" what do you think would be an ideal distance for 2 in a 5x5?

Mars-Hydro overstates the capabilities of their lights. The light you mention draws 395w. Being generous, that all that power goes to the LEDs (not fans nor drivers), that would be 25w per sq ft. There is absolutely no way inefficient epi-whatever diodes will flower decently at that level. They need to be about 45w/sq ft in flower (30-35 works in veg). 55 works better.

Epi-whatever diodes aren't much better than CFLs in reflectors. At the low end, that light will cover 3x3 in flower (44w/sq ft).

Instead of buying more innefficient Mars-Hydro, I'd recommend rigging up some Cree PAR38 spots/floods around the perimeter. They are relatively efficient. I've done very well at 21w/sq ft in flower. But, 25-30 would be better. If the Mars-Hydro covers 3x3 (9 sq ft) then you have 7 additional sq ft to cover a 4x4 (16 sq ft). At 30w sq ft, that would be 210w. The PAR38s are 18w. That's 11-12 lights. That would be a bit of work rigging up the mounts. But, they'll come in handy for flexible, long-term sidelighting in the future (regardless of what you use as your primary source of light).

To be honest, a CMH would have been a better investment than Mars-Hydro. (Or, T5HO in a short space.). I hope it works out for you.

Anybody out there with experience using Mars hydro products?

I have never used LEDs but have used many diffent types of lights to grow weed and the one thing they all have in common is they need to be close to the top of the canopy
if i was you reduce the canopy size down to 3ft x 3ft and put both leds side by side 12" above the canopy

good luck, maybe you will get lucky and sombody that uses leds will give you better advice

Hi Chris
I am on my first indoor grow with a 300w Galaxyhydro LED. It comes down to finding one's sweet spot as regards to INTERNODE spacing via strain with LED lights. I have kept mine an average height above canopy of 12" throughout vegging with no issues. I am not photo bombing or jacking but here's a pic of plant that was a seed in hand Oct 5th. I have no complaints with LED.

Krippled said:

Hi Chris
I am on my first indoor grow with a 300w Galaxyhydro LED. It comes down to finding one's sweet spot as regards to INTERNODE spacing via strain with LED lights. I have kept mine an average height above canopy of 12" throughout vegging with no issues. I am not photo bombing or jacking but here's a pic of plant that was a seed in hand Oct 5th. I have no complaints with LED.View attachment 3564343

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So wattage really isn't a problem here? Like in the case of HID lighting, the higher the bulb the higher you would have your light. Is this irrelevant with LEDS? Basically I just have to play around till I find the sweet spot?

Chrisz0825 said:

So wattage really isn't a problem here? Like in the case of HID lighting, the higher the bulb the higher you would have your light. Is this irrelevant with LEDS? Basically I just have to play around till I find the sweet spot?

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There is a "focus" to your fixture. Mars-Hydro probably advises you correctly on that. But, w/sq ft will matter. I use LED and these epi-whatever fixtures don't produce well unless they're concentrated at the wattages I mentioned above. Buds tend to be airy. Not terrific for taller plants.

The problem with spending another $320 on one of those is that the footprint (of two) doesn't work in that space. You'd be better off with 4 smaller units. (Or, like I said, even better with CMH.).

Actually, four of those 295w lights for 5x5 would work ok. That would be 1180w at 47.5w/sq ft. But, it will be hot.

But, for $1280. But, I'd be reluctant to spend that kind of money on epi-whatever lights. @REALSTYLES bout a dozen or more about a year ago. That turned out to be a total loss for him. There are reports of Mars-Hydro not honoring the warranty. (Their warranty used to say they would decline service if you "spread bad words" about their product. That could be what happened. It might depend on your demeanor.).

Trying one isn't a lot of money to put at risk. But, when you sink a lot into it....

You can get into CMH covering 3x3 at 35-40w/sq ft for $250. Use the Mars Hydro to fill in. The nice thing about the CMH (aside from being more efficient) is that it's a long-term investment. Just replace the bulb occasionally ($50).

Yeah $500 for one unit is crazy high, if I had to pay that much I would of went one 600 hps. I have $290 for two 300w LEDs..

Krippled said:

Yeah $500 for one unit is crazy high, if I had to pay that much I would of went one 600 hps

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I mis-typed. It's $320. (My mistake! I was just editing that post when you posted!).

It's not bad to try one of these imported epi lights. It's not a lot of money to lose on a learning experience. I went that path with Blackstar (more expensive, but still epi-whatever) and a custom-spectrum Apollo.

I think the first question anyone considering LED should ask is: why? Is it just to be high-tech? If it's to reduce heat and electrical cost, you have to pay for higher-end LEDs like Area-51, Hans Bonsai, Tasty. Otherwise, CMH is more cost beneficial for taller spaces (T5HO for shorter spaces).

I like the Cree lightbulbs for short spaces (but, I've grown a tall plant at 21w/sq ft and it did well.). But, most people don't have a desire to rig up a lot of bulbs like that. It's not too feasible in a 5x5 tent. I've thought of using a "fixture" of 1x4 planks of wood with sockets attached every foot. One "rail" every foot. That would make it more manageable. But, still kind of hokey.

I wouldn't put more money into Mars-Hydro until seeing how one fixture works. Buy an Area51 to compare to. Or, rig up a Cree lightbulb fixture to cover a 2x2 space (25-30w/sq ft) and compare to that. It's good to have a few things in the toolbox. They always come in handy as backups, fill in dark areas, etc.

I don't plan on growing a lot at a time. I really just wanna grow 4 plants at a time. So I feel that 2 of the 192x5 reflectors would cover just about all 4 plants. Being side by side I feel the outer footprints would overlap each other increasing the actual wattage that section would be receiving without the second light

one would cover 2 plants fine. i'd use both. you can't have too much light. (well, you can but keep an eye out for leaves turning white) .

you could probably get between 6 to 12 inches from the plant tops. i could with my 5 w leds. get a fan to keep the tops cool.

rkymtnman said:

one would cover 2 plants fine. i'd use both. you can't have too much light. (well, you can but keep an eye out for leaves turning white) .

you could probably get between 6 to 12 inches from the plant tops. i could with my 5 w leds. get a fan to keep the tops cool.

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Awesome. Thank you very much for your response. This is exactly the answer I was looking for

Chrisz0825 said:

Awesome. Thank you very much for your response. This is exactly the answer I was looking for

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i'd flip them to 12/12 when they get about 5 to 6 inches tall. you leds will grow some good bud down to about 12" of canopy. maybe trim a few big fan leaves but dont' go overboard with the trimming.

rkymtnman said:

i'd flip them to 12/12 when they get about 5 to 6 inches tall. you leds will grow some good bud down to about 12" of canopy. maybe trim a few big fan leaves but dont' go overboard with the trimming.

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Oh boy I guess I may have let mine veg to long as it was 8.5 weeks 20" in height before I flipped last week???

az2000 said:

Mars-Hydro overstates the capabilities of their lights. The light you mention draws 395w. Being generous, that all that power goes to the LEDs (not fans nor drivers), that would be 25w per sq ft. There is absolutely no way inefficient epi-whatever diodes will flower decently at that level. They need to be about 45w/sq ft in flower (30-35 works in veg). 55 works better.

Epi-whatever diodes aren't much better than CFLs in reflectors. At the low end, that light will cover 3x3 in flower (44w/sq ft).

Instead of buying more innefficient Mars-Hydro, I'd recommend rigging up some Cree PAR38 spots/floods around the perimeter. They are relatively efficient. I've done very well at 21w/sq ft in flower. But, 25-30 would be better. If the Mars-Hydro covers 3x3 (9 sq ft) then you have 7 additional sq ft to cover a 4x4 (16 sq ft). At 30w sq ft, that would be 210w. The PAR38s are 18w. That's 11-12 lights. That would be a bit of work rigging up the mounts. But, they'll come in handy for flexible, long-term sidelighting in the future (regardless of what you use as your primary source of light).

To be honest, a CMH would have been a better investment than Mars-Hydro. (Or, T5HO in a short space.). I hope it works out for you.

Click to expand...

No I just had 2 Mars II-1600s, 1-1200, 1-900 and 2 Mars 3watt 300s. I actually had a wash I didn't lose money nor made money. Ijust wasted my time with those light lol

I wanna use the scrog method and I hear you should let your plants fill the space before you flip. I was gonna put the scrog net up about 2 feet or so. Would this be a no no with these lights? I really wanna achieve the biggest yield. Which is why I wanna use a scrog and FIM my plants. Maybe even super crop

For what it's worth, I too use LEDs. I have a 400W OceanRevive panel ($188 from Amazon) and 2 T5HOs hanging on the sides. I get plenty decent of bud, tent is only 32"x32"x63", so space is limited. I grew the plant in picture to the left from seed and got 3.75 oz. Had to cut early cuz of caterpiilars, it was outside for 4 months. The two previous grows each yeilded 3.5 oz. each, right now got OG Kush clone 14 days into flower. Top, supercrop and LST to keep height down, lots of bud sites. Should be able to break the 1/4 lb barrier.

Krippled said:

Yeah $500 for one unit is crazy high, if I had to pay that much I would of went one 600 hps. I have $290 for two 300w LEDs..

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I was about to say. I have a few air couple 600w hps setups I'll could sell for less than $250.


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oh yeah forgot to add light distance. I go about 6 inches, if I go further away the plant seems to stretch too much. Could depend on strain. jmho